Nancy Braches on sun 27 aug 06
Well I mixed my own glazes this week and ran a test fire the floating blue and 3 versions of it, raspberry, honey all beautiful.
I found a "simple" blue recipe in the archives and mixed it up...expecting the beautiful blue and it is clear. So I am sure the fix is simple...some cobalt or something. Can anyone offer a suggestion? Here is the recipe I used:
Gerstley 13%
Flint/Silica 26.3%
Kaolin 5%
Bentonite 2.5% (optional)
Feldspar F4 36.1%
Talc 6.4%
Zinc Oxide 5.1%
Whiting 8.1%
Adds up to 102.5% (I think because bentonite is optional)
Any input would be greatly appreciate as I venture into simple glazemaking.
Nancy
Hilltop Pottery
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Dannon Rhudy on mon 28 aug 06
The blue glaze is missing cobalt. Add some. How
much depends on the depth of blue you want to achieve.
Start with 1/4 of 1% for a light to medium blue, depends
on the amount of glaze on the piece and the glaze itself.
regards
Dannon Rhudy
> I found a "simple" blue recipe in the archives and mixed it up...expecting
the beautiful blue and it is clear.
Megan Mason on mon 28 aug 06
you have the base glaze .I wonder if you go back to the recipe if you will
see they have cobalt, at least ,as a colorant. If not published, start with
.25 and run some tests,adding a small increaing amount each level.You might
also try some cobalt carbonate as well as oxide as the results can differ
and the oxide is almost twice as strong and .25 is a good bet for the
oxide.I would get the amount of oxide down to the lowest amount to get the job
done as it is so pricy.Tests with an opacifier like zircopax or equivalents or
increasing amounts of prouder rutile or wood ash might be further avenues to
explore for fun..
Meg
In a message dated 8/28/2006 12:10:17 A.M. Eastern Standard Time,
hilltoppottery@YAHOO.COM writes:
Well I mixed my own glazes this week and ran a test fire the floating blue
and 3 versions of it, raspberry, honey all beautiful.
I found a "simple" blue recipe in the archives and mixed it up...expecting
the beautiful blue and it is clear. So I am sure the fix is simple...some
cobalt or something. Can anyone offer a suggestion? Here is the recipe I used:
Gerstley 13%
Flint/Silica 26.3%
Kaolin 5%
Bentonite 2.5% (optional)
Feldspar F4 36.1%
Talc 6.4%
Zinc Oxide 5.1%
Whiting 8.1%
Adds up to 102.5% (I think because bentonite is optional)
Any input would be greatly appreciate as I venture into simple glazemaking.
Nancy
Hilltop Pottery
Steve Slatin on mon 28 aug 06
Nancy --
Just a quick off-the-cuff analysis -- your recipe has nothing in it to
make it blue. There are blue glazes that come from blue colorants
(typically cobalt oxide or carbonate) and there are blues that come
from diffraction of light through tiny bubbles in the glaze (chun-type
glazes) and there are 'floating blue' glazes where the blue comes
from the phase shift between boron-rich and primarily silicate glasses.
I think you're a little low on gerstley to get a floating blue in the recipe
below, and there's no cobalt. Zinc does funny things in a
glaze -- it fluxes things rather well, it changes colors, and it opacifies.
The one glaze I make with zinc and cobalt gives me a lavender color
rather than a 'true' blue.
So, as quick fixes go, if I had your problem I'd start with 1% cobalt
carbonate and glaze a test tile with it. Do be cautious with cobalt; it
is a powerful flux itself. Add too much and your glaze will become
quite runny.
Best wishes -- Steve S
Nancy Braches wrote:
Well I mixed my own glazes this week and ran a test fire the floating blue and 3 versions of it, raspberry, honey all beautiful.
I found a "simple" blue recipe in the archives and mixed it up...expecting the beautiful blue and it is clear. So I am sure the fix is simple...some cobalt or something. Can anyone offer a suggestion? Here is the recipe I used:
Gerstley 13%
Flint/Silica 26.3%
Kaolin 5%
Bentonite 2.5% (optional)
Feldspar F4 36.1%
Talc 6.4%
Zinc Oxide 5.1%
Whiting 8.1%
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Gary Harvey on mon 28 aug 06
yes, Cobalt is missing I'd try 1%,2% upto 3%. Yes bentonite is optional but
I'd put it in if I were you. The bentonite helps the glaze stay in
suspension and also helps with the thickness of the glaze. For example the
floating blue is better on the thick side. Good luck GH Palestine TX
----- Original Message -----
From: "Nancy Braches"
To:
Sent: Sunday, August 27, 2006 3:24 PM
Subject: Blue Glaze missing something??
> Well I mixed my own glazes this week and ran a test fire the floating blue
> and 3 versions of it, raspberry, honey all beautiful.
>
> I found a "simple" blue recipe in the archives and mixed it up...expecting
> the beautiful blue and it is clear. So I am sure the fix is simple...some
> cobalt or something. Can anyone offer a suggestion? Here is the recipe I
> used:
>
> Gerstley 13%
> Flint/Silica 26.3%
> Kaolin 5%
> Bentonite 2.5% (optional)
> Feldspar F4 36.1%
> Talc 6.4%
> Zinc Oxide 5.1%
> Whiting 8.1%
>
> Adds up to 102.5% (I think because bentonite is optional)
>
> Any input would be greatly appreciate as I venture into simple
> glazemaking.
>
> Nancy
> Hilltop Pottery
>
>
>
> ---------------------------------
> Talk is cheap. Use Yahoo! Messenger to make PC-to-Phone calls. Great
> rates starting at 1¢/min.
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
Nancy Braches on mon 28 aug 06
Meg
Sounds like fun with glaze :) I do have the oxide and yep it sure is pricey but I also have the carbonate and rutile. I'm gonna break up the glaze into smaller portions and play.
Nancy
Hilltop Pottery
Megan Mason wrote:
you have the base glaze .I wonder if you go back to the recipe if you will
see they have cobalt, at least ,as a colorant. If not published, start with
.25 and run some tests,adding a small increaing amount each level.You might
also try some cobalt carbonate as well as oxide as the results can differ
and the oxide is almost twice as strong and .25 is a good bet for the
oxide.I would get the amount of oxide down to the lowest amount to get the job
done as it is so pricy.Tests with an opacifier like zircopax or equivalents or
increasing amounts of prouder rutile or wood ash might be further avenues to
explore for fun..
Meg
In a message dated 8/28/2006 12:10:17 A.M. Eastern Standard Time,
hilltoppottery@YAHOO.COM writes:
Well I mixed my own glazes this week and ran a test fire the floating blue
and 3 versions of it, raspberry, honey all beautiful.
I found a "simple" blue recipe in the archives and mixed it up...expecting
the beautiful blue and it is clear. So I am sure the fix is simple...some
cobalt or something. Can anyone offer a suggestion? Here is the recipe I used:
Gerstley 13%
Flint/Silica 26.3%
Kaolin 5%
Bentonite 2.5% (optional)
Feldspar F4 36.1%
Talc 6.4%
Zinc Oxide 5.1%
Whiting 8.1%
Adds up to 102.5% (I think because bentonite is optional)
Any input would be greatly appreciate as I venture into simple glazemaking.
Nancy
Hilltop Pottery
______________________________________________________________________________
Send postings to clayart@lsv.ceramics.org
You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/
Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
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Ron Roy on tue 29 aug 06
Hi Nancy,
Yes - try some cobalt carb - start with 1/2 of a % and work up to one % and
I recommend trying it with some rutile as well like 5%
This is a well balanced glaze - expansion is neither high or low - enough
alumina and silica that it is probably stable if not too much colouring
oxides are added.
It is relying on both boron and zinc to melt properly at cone 6.
If it's pinholing - it's probably because the zinc is getting reduced so
firing it with a vent on will be best.
I would recommend including the bentonite - 5% kaolin is minimal to keeping
the glaze from settling fast.
RR
>Well I mixed my own glazes this week and ran a test fire the floating blue
>and 3 versions of it, raspberry, honey all beautiful.
>
>I found a "simple" blue recipe in the archives and mixed it up...expecting
>the beautiful blue and it is clear. So I am sure the fix is simple...some
>cobalt or something. Can anyone offer a suggestion? Here is the recipe I
>used:
>
>Gerstley 13%
>Flint/Silica 26.3%
>Kaolin 5%
>Bentonite 2.5% (optional)
>Feldspar F4 36.1%
>Talc 6.4%
>Zinc Oxide 5.1%
>Whiting 8.1%
>
>Adds up to 102.5% (I think because bentonite is optional)
>
>Any input would be greatly appreciate as I venture into simple glazemaking.
>
>Nancy
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
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